High-Voltage Connections; Routing Power Leads Into Unit; Routing Control Power Wires (24-V); Special Procedures For 208-V Operation - Carrier 50SZ Series Installation, Start-Up And Service Instructions Manual

Single-packaged heat pump units
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INSTALLATION REQUIREMENTS
Failure to follow these precautions could result in damage to
the unit being installed:
1. Make all electrical connections in accordance with NEC
ANSI/NFPA (latest edition) and local electrical codes
governing such wiring. In Canada, all electrical connec-
tions must be in accordance with CSA standard C22.1
Canadian Electrical Code Part 1 and applicable local
codes. Refer to unit wiring diagram.
2. Use only copper conductor for connections between
field-supplied electrical disconnect switch and unit. DO
NOT USE ALUMINUM WIRE.
3. Be sure that high-voltage power to unit is within operating
voltage range indicated on unit rating plate. Consult local
power company for correction of improper voltage.
4. Insulate low-voltage wires for highest voltage contained
within conduit when low-voltage control wires are in same
conduit as high-voltage wires.
5. Do not damage internal components when drilling through
any panel to mount electrical hardware, conduit, etc.

HIGH-VOLTAGE CONNECTIONS

The unit must have a separate electrical service with a field-
supplied, waterproof disconnect switch mounted at, or within sight
from the unit. Refer to the unit rating plate, NEC and local codes
for maximum fuse/circuit breaker size and minimum circuit amps
(ampacity) for wire sizing (See Table 3 for electrical data).
The field-supplied disconnect may be mounted on the unit over the
high-voltage inlet hole (See Fig. 2 and 3).
If the unit has an electric heater, a second disconnect may be
required. Consult the Installation, Start-Up, and Service Instruc-
tions provided with the accessory for electrical service connec-
tions.
Operation of unit on improper line voltage constitutes abuse and
may cause unit damage that could affect warranty.

ROUTING POWER LEADS INTO UNIT

Use only copper wire between disconnect and unit. The high-
voltage leads should be in a conduit until they enter the duct panel;
conduit termination at the duct panel must be watertight. Run the
high-voltage leads through the power entry knockout on the power
entry side panel. See Fig. 2 and 3 for location and size. When the
leads are inside the unit, run leads up the high-voltage raceway to
the line wiring splice box (See Fig. 13). For single-phase units,
connect leads to the black and yellow wires (See Fig. 14).
CONNECTING GROUND LEAD TO GROUND SCREW
Connect the ground lead to the chassis using the ground screw in
the wiring splice box (See Fig. 14).

ROUTING CONTROL POWER WIRES (24-V)

Form a drip-loop with the thermostat leads before routing them
into the unit. Route the thermostat leads through grommeted,
low-voltage hole provided in unit into unit control power splice
box (See Fig. 2 and 3). Connect thermostat leads to unit control
power leads as shown in Fig. 13.
The unit transformer supplies 24-v power for complete system
including accessory electrical heater. An automatic-reset circuit
breaker (See Fig. 15) is provided in the 24-v circuit; see the caution
label on the transformer. Transformer is factory wired for 230-v
operation. If supply voltage is 208-v, rewire transformer primary
as described in Special Procedures for 208-v Operation section.

SPECIAL PROCEDURES FOR 208-V OPERATION

1. Disconnect the yellow primary lead from the transformer. See
unit wiring label (See Fig. 12).
2. Connect the yellow primary lead to the transformer terminal
labeled 200-v.
Indoor blower-motor speeds may need to be changed for 208-v
operation. Refer to indoor airflow and airflow adjustments section.

PRE-START-UP

FIRE, EXPLOSION, ELECTRICAL SHOCK HAZARD
Failure to observe the following warnings could result in
serious personal injury or death:
1. Follow recognized safety practices and wear protective
goggles when checking or servicing refrigerant system.
2. Do not operate compressor or provide any electric power to
unit unless compressor terminal cover is in place and
secured.
3. Do not remove compressor terminal cover until all electri-
cal sources are disconnected and tagged.
4. Relieve and recover all refrigerant from system before
touching or disturbing anything inside terminal box if
refrigerant leak is suspected around compressor terminals.
5. Never attempt to repair soldered connection while refrig-
erant system is under pressure.
6. Do not use torch to remove any component. System
contains oil and refrigerant under pressure.
To remove a component, wear protective goggles and
proceed as follows:
a. Shut off electrical power to unit and install lockout tag.
b. Relieve and reclaim all refrigerant from system using
both high- and low-pressure ports.
c. Cut component connecting tubing with tubing cutter and
remove component from unit.
d. Carefully unsweat remaining tubing stubs when neces-
sary. Oil can ignite when exposed to torch flame.
Use the Start-Up Checklist supplied at the end of this book and
proceed as follows to inspect and prepare the unit for initial
start-up:
1. Remove access panel.
2. Read and follow instructions on all DANGER, WARNING,
CAUTION, and INFORMATION labels attached to, or
shipped with, unit.
Transformer contains a manual reset overcurrent protector.
It will not automatically reset. Disconnect power and install
lockout tag prior to servicing. This compartment must be
closed except when servicing.
3. Make the following inspections:
a. Inspect for shipping and handling damages such as broken
lines, loose parts, disconnected wires, etc.
b. Inspect for oil at all refrigerant tubing connections and on
unit base. Detecting oil generally indicates a refrigerant
leak. Leak-test all refrigerant tubing connections using
electronic leak detector, or liquid-soap solution. If a refrig-
erant leak is detected, see following Check for Refrigerant
Leaks section.
c. Inspect all field and factory-wiring connections. Be sure
that connections are completed and tight.
d. Ensure wires do not touch refrigerant tubing or sharp
sheetmetal edges.
9

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